1. Field of the Invention
The present invention relates to an image forming apparatus, an image forming method, and a non-transitory computer-readable storage medium.
2. Description of the Related Art
Liquid ejection recording that uses a recording head, e.g., a liquid ejection head (liquid-droplet ejection head) that ejects liquid droplets, is commonly employed in image forming apparatuses such as printing machines, facsimile machines, copying machines, plotting machines, and multifunction peripherals having two or more functions of these machines. Known examples of such an imaging forming apparatus include inkjet recording apparatuses.
In an image forming apparatus that forms an image using a recording head mounted on a carriage driven to reciprocate, it is necessary to stop the moving carriage immediately upon occurrence of an abnormal condition, such as contact between the carriage and paper (hereinafter, “paper floating”) elastically bent in a manner to bulge toward the carriage or a foreign matter unintentionally entered the apparatus.
Under the circumstance, there is a conventionally known technique for driving a carriage by performing operations including: obtaining position/velocity information about the carriage using a linear encoder while calculating position/velocity command values; feeding back the values and the information; determining a drive condition of the carriage based on a difference between the position/velocity command values and current position/velocity values of the carriage; and stopping the carriage when the difference exceeds a permitted value. An example of this technique is disclosed in Japanese Laid-open Patent Application No. 2006-240026.
However, an image forming apparatus that applies high driving power onto a carriage or includes a carriage whose weight is large can encounter a situation where a position/velocity of the carriage remains unchanged even when contact between the carriage that is moving and floating paper or a foreign matter occurs.
In such a situation, the configuration disclosed in Japanese Laid-open Patent Application No. 2006-240026 disadvantageously fails to immediately stop the carriage, causing an ejection surface of a recording head and/or the carriage to be damaged.
Therefore, it is desirable to provide an image forming apparatus that allows immediate detection of contact between a carriage that is moving and paper or a foreign matter and, upon detection, stopping the carriage.